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Ethical dilemmas: is walking more polluting than driving?

Justin Rowlatt | 10:13 UK time, Monday, 16 March 2009

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Las Vegas, Nevada - The rule of our journey around America is straightforward: where there is a choice we take the low-carbon option. It sounds simple but making the right choice can be difficult.

Here is a case in point. On Tuesday I met my first bona fide billionaire, the oil-man turned wind energy tycoon, T Boone Pickens.

I interviewed him in his Dallas office and, as we chatted afterwards, I mentioned we were heading off to Las Vegas. Boone, being a true Oklahoma gentleman, promptly offered us a lift... on his private plane!

My other attempt at hitch-hiking, back in Detroit, ended with me being stopped by the police. Boone was much more accommodating. He said he was going to Phoenix early Friday morning and would be happy to get his plane to drop us in Vegas.

What a dilemma! Two hours relaxing in the soft leather seats of a billionaire's private jet or 20 hours behind the wheel of a hire car (there is no connecting train and at 28 hours, we judged the Greyhound just too time consuming).

It should be a straightforward calculation: Boone was already going to Phoenix so it is the marginal increase in jet fuel against the emissions of the petrol consumed by a car making the 1,200 mile journey by road.

It is a much more glamorous version of the sort "ethical" dilemma I became far too familiar with during the year my family and I lived as Ethical Man. What I learned then is that these calculations are rarely as simple as they seem.

I stumbled across a great example of this last year. In the spirit of recycling I have lifted it straight from a blog by a guy called Brad Templeton.

Brad explains that the average person uses about 100 calories per mile walking at 3 mph - 300 calories per hour. By comparison sitting burns 80 calories an hour. In other words, walking three miles takes an extra 220 calories.

Now, a (US) gallon of gasoline has about 31,500 calories so the conclusion might be that a human walking gets around 400 mpg. But, as Brad points out, that ignores the fossil fuels that go into producing the food we eat.

Brad claims US agriculture uses about 400 gasoline-gallon equivalents per American per year (if anyone can source this figure I would be very grateful). So that is 1.1 gallons a day to produce the 2700 calories that form the average American's diet or 10 calories of fossil fuel for each calorie of food consumed. That is right: 10 fuel calories for each food calorie! It is a shocking statistic isn't it?

Justin ruins his suitYou will have guessed where this is going: walking 3 miles uses 220 extra calories over sitting, but sucks up 2,200 calories of fossil fuel. This means you get just 42 mpg as you stroll. Some small cars are more efficient.

And, if you eat a lot of burgers, the figures are even worse. Your fuel consumption rises dramatically because 40 calories of fuel energy are used per calorie of beef. If you only ate beef you would not only be very unhealthy, you would get just 10 mpg as you walked, worse than a Humvee!

On this basis the correct choice would be for the Ethical Man team to drive rather than walk whenever possible (sharing a vehicle dramatically improves fuel efficiency).

Nonsense, of course, but Brad's calculations make an important point - and not just that modern agribusiness uses an extraordinary amount of energy. You may quibble with some of his figures but his example shows just how complex it is can be to work out the carbon cost of different activities.

Which is why the arguments for cap-and-trade can be compelling. If we have to pay to emit carbon dioxide it will be much easier to make the environmental choice because the low carbon option will become the cheaper option.

PigswillAt the moment prices reflect the scarcity of fossil fuels, which is why I was able to afford to buy a return ticket from Los Angeles to London this weekend (it cost just £400, plus £40 for a carbon offset). That's right, I have flown home for the weekend!

I have to host a charity dinner which was arranged before we planned our American odyssey. (It is for my wife's favourite charity, Friends of Colombia for Social Aid, if you are interested.) I will also get to spend a few hours with my lovely family who I have been missing terribly over the last three weeks.

But the question I opened this blog with was about a billionaire's private jet, not me missing my family.

So did we accept Boone's kind offer? We did not, but not because of concerns about the carbon cost. I mean, how many times have you been offered a ride to Vegas in a billionaire's private jet?

Bob Combs and JustinThe reason did not accept was because Boone was flying on Friday and we had arranged to meet Las Vegas' only pig farmer and one of Nevada's leading food recyclers on Thursday morning.

The farmer, Bob Combs, is a perfect example of conservation in action. He collects the food waste from the ludicrously extravagant buffets laid on by Las Vegas hotels and then cooks it up and feeds it to his pigs. His hogs recycle some of those food calories that so concern Brad Templeton.

Judge for yourself whether we were right to forgo the jet and meet Bob. And, of course, feel free to comment below. You can complain about my decision to take a break from this trip and catch a plane home or maybe even sympathise with me. Did I make the right choice?


  • Comment number 1.

    A tricky one - especially when one knows that so many scheduled flights are currently travelling [not traveling..] half empty, or even totally empty if their 'landing slot' is at risk...

    But then there might not be any vegetarians if all meat-eaters thought that way, with the consequent impact on those 'pig-recyclers'...

  • Comment number 2.

    By the way - I know this criticism has been levelled at you before, but..

    Surely if you are [were?] the 'Ethical Man', not just the 'Green Man' you should be covering such things as 'fairtrade', Export Processing Zones, child labour making trainers and clothes, 'organic' cotton and much more besides ?

  • Comment number 3.

    I know this isn't exactly relevant to this challenge but please consider looking at the Honda Clarity. I've been banging on about it but so far no one has acknowledged this on these pages. It really is a revolution unlike the Chevy volt which is just a better hybrid (and if you ask me is what the Prius should have been all long). I mean, a Prius gets 60mpg, wow so does a Polo Blue motion, and the Lexus 4x4 hybrid has CO2 of 180 which is the same as vRs sports car!

    Part of the problem are those heavy Li-on batteries. In laptops these could soon be replaced by combustion devices which are far more efficient:

    Oh btw in answer to your question: Hey I'm a Sceptic, feel free!

  • Comment number 4.

    I never eat pork. It is the most toxic meat anyone can eat. Your video and picture of "pig feed" are good visual proof, but there is plenty of written documentation. Thanks for the report.

  • Comment number 5.

    The '400 gallons per person' figure is from 'Food, Land, Population and the U.S. Economy' published by Pimentel, David and Giampietro, Mario, 1994

  • Comment number 6.

    Nice comments about the walking. I wonder if Brad Templeton considered the health benefits and if not going to the hospital for a heart attack later on would increase your usage. Though technically if you die earlier you may be better for the envirionment depending on the care you receive at the end.

  • Comment number 7.

    Does this suit you keep messing up need to be dry cleaned?
    Single engine piston airplanes get 20 miles per gallon, in some cases, even though they're flying at 180 miles per hour. To find out whether to jump a ride with T. Boone, you would have to find out what kind of jet he's flying. Smaller Cessna Citations are very efficient, Gulfstream IIs substantially less so. Mr. Pickens is a bit on the tall side, so Citations are a bit of a scrunch.
    Another way of looking at your activity is: in the messages you're broadcasting and posting, is this changing behavior in ways that is more or less polluting? Have you influenced behavior that has reduced fuel use by a large number of people? If so, you're home free. I can think of a number of TV programs that tend to promote consumption (telenovellas and their derivatives) that would be working in the opposite direction of your aim. The first thing people have to do is consider the effects of their behavior.

  • Comment number 8.

    "And, if you eat a lot of burgers, the figures are even worse. Your fuel consumption rises dramatically because 40 calories of fuel energy are used per calorie of beef. If you only ate beef you would not only be very unhealthy, you would get just 10 mpg as you walked, worse than a Humvee!"

    Hmmm... This statement, while provocative, is a "walking contradiction". While it is amusing to think of ourselves as vehicles in the grand scheme of things, aren't we forgetting something?

    There are plenty of people who consume an excess of 3,000 calories yet sit on the couch all day, not burning much off. Yet others may be consuming only 1,000 calories and powerwalking for 4 hours.

    Perhaps we should encourage anorexia to get that human mpg closer to your goal? :)

    Likewise, the source of calories (which you pointed out) plays a significant role. One who walks from 5th avenue to Madison Ave (1 block) to devour an ounce of caviar from the gourmet grocery would obviously be using an exorbitant amount of energy in comparison with a rural farmer walking his land and gathering the harvest.

    Needless to say, there is more than meets the eye...

  • Comment number 9.

    "Brad's calculations make an important point"

    Point being to understand when calculations are obfuscations.

    Here is another one based on Brad's numbers:
    Starting with:
    " 1.1 gallons a day to produce the 2700 calories that form the average American's diet"

    So walking 24 hrs at 4m/hr gives 96 miles on this 1.1 gallon,
    or 87 miles/gallon
    Much better than a hybrid! Enjoy your walking, but take a rest to save some calories for thinking :-)


  • Comment number 10.

    Is that a dead dog, top centre of the 'pigswill' picture ?

  • Comment number 11.

    Your comparison is invalid. If you are going to factor in the energy-equivalents required to make the food, then you must also factor in the energy-equivalents required to make the automobile. If you do, then you will discover that walking is the correct 'green' route.

    Dr. Smith, working on greenhouse-gas sequistration.

  • Comment number 12.

    A most interesting blog, especially claiming walking consumes more CO2 than driving in certain cases. Brad Templeton makes a compelling case for the enormous consumption (and thus CO2 emission) of agriculture, which then must be passed onto the humble pedestrian. But a crucial factor that is omitted in this line of reasoning is that agriculture absorbs CO2 since every plant uses photosynthesis whereas fossil fuel use only produces CO2.

  • Comment number 13.

    I don't believe that you can make a reasonable comparison between the energy used by traveling on foot and that used by traveling in a gas-powered vehicle. A human's metabolism and muscles will improve in efficiency while an engine does not. In my case, I've found that the more I adapt to an endurance activity the fewer calories I need to sustain it. Anyone who cycles could confirm this. You start out exhausted by a 30 mile ride in the spring, and by summer it's a warm-up that barely merits a snack.

  • Comment number 14.

    As has been hinted at above, people will not necessarily eat more, just because they have exercised more. They may eat the same amount (or less), and become healthier, which should (if a large enough percentage of the population follows suit) reduce the carbon foot-print of hospitals.

    Nice to see someone (papabearsmith), thinking about entire lifecycle carbon footprints. Electric private motor vehicles will not significantly reduce carbon emissions, unless they can be made be using the same amount of energy as is used to make a bicycle.

  • Comment number 15.

    The '400 gallons per person' figure is from 'Food, Land, Population and the U.S. Economy' published by Pimentel, David and Giampietro, Mario, 1994

    But where did they get their numbers from... they don't say in their piece.

    Driving is not the same as sitting, sitting and reading burns nearly 100 cal but driving is more active and stressful than reading. The fuel efficiency of a vehicle is calculated assuming it is warmed up and over a long trip, for a 3 mile trip (the 1 hour of walking) it would be very poor particularly in an urban setting.

    Even so, for an average type of diet you'd be better off with public transport or maybe a shared taxi than walking. Then again what about the bicycle, much more efficient than walking and in many towns just as quick as a car.

    The real trick is diet, the production of many popular foods take advantage of cheap fuel costs. Also the average American eats 2700 cal a day, that is too much and fails at the first stage of the hierarchy: reduce, reuse, recycle.

    Above someone jokes that if we were all anorexic then we'd burn far fewer calories but you don't have to be mentally ill to eat less and in turn slow your metabolism. Most of us do not have jobs that demand high metabolism, the brain works fine at slow metabolic rates and eating less calories is the only demonstrated way to extend life. You can even maintain healthy levels of activity.

  • Comment number 16.

    If you have questions, I do hope you will click through to the original article talked about. I do of course consider the health value of walking and cycling and for all but the most extremely fit, there is no suggestion you should drive rather than walk. Instead, it's an expression of just how energy intensive agriculture has become in the USA (and other places) and what it implies.

    If you live on beefsteak from factory farms, you are burning a lot of fossil fuel energy to get your calories. If you eat organic vegetables from your garden you're doing quite well.

    It's also much more important, though I don't explore it in this post, to care about how something is farmed rather than where it is farmed. Shipping is a tiny part of the energy equation of the food. Well farmed food shipped by boat from New Zealand will use less energy than factory farm food from nearby.

    I must admit I went on the study cited above so I can't confirm the details of their research. However, even if their numbers are off by a significant amount, the amount of fuel in agriculture is still something to worry about. From other sources, I have learned that about 5% of all natural gas goes to making artificial fertilizer. (The rest goes to heat homes and make electricity.)

  • Comment number 17.

    You say "I was able to afford to buy a return ticket from Los Angeles to London this weekend (it cost just £400, plus £40 for a carbon offset)."
    Perhaps this has been explained before, but what happens with the £40 you paid as a carbon offset? How can you be sure that it's being spent as ethically to reduce carbon output and not (for example) to offset government debt?

  • Comment number 18.

    What a dilemma! Two hours relaxing in the soft leather seats of a billionaire's private jet or 20 hours behind the wheel of a hire car

    One faced by many around the world, daily, I'm sure. Along with the other daunting choices faced. Has Mr. Harrabin got back from his scuba diving trip yet? Message and messengers again spring to mind.

  • Comment number 19.

    Yes, you were right to fly home. No matter the controversy you are covering at the moment, keep priorities straight.

    Now. If everyone reading will walk a couple of times this week instead of reaching for the car keys we will handily offset your trip home with our own carbon savings... count me in =-)

  • Comment number 20.

    I'm sensing reduction is kind of off the menu for some, if more than for others.

  • Comment number 21.

    I think that both Walking and Driving are in the league of pollution....
    ~Dennis Junior~

  • Comment number 22.

    The proposition that walking consumes more energy than driving is to me not true.

    Here in the Philippines, I regularly prepare meals for me and my family at about $0.20 or less per head per meal. This is at most $0.60 per head per day, much less than the $$4 just for a gallon of gasoline equivalent the proponent says is consumed to produce, process, transport and prepare the daily food of every American.

    Lest you think the food we eat here is from inexpensive local organically-grown ingredients, here is its breakdown per person per meal:

    50 grams of factory-grown animal protein (chicken, fish or egg);

    135 dry grams of rice shipped in from the intensively-fertilized plantations of Thailand (it would have been cheaper by half had not importers jack up the price so local rice farmers can compete with it);

    greens intensively grown from 200km away;

    oil to saute the lot, salt, soy sauce and other condiments; and

    the gas (shipped from as far as the Indian Ocean)to cook with.

    Maybe the one who came up with the data took into account even the total gas consumption of the restaurant/catering industries,its members and their families, and the gas consumed by housewives who cook the meals (pro-rated according to the hrs they spent cooking).

  • Comment number 23.

    Hey Justin! I'm a big fan of BBC, probably one of the few down here in Colombia. I've seen your show and this is the first time I was compelled to sing in into a Blog (any blog). Your show is fantastic and I truly believe your efforts in cutting carbon emissions and teaching people with BBC's help will have a favorable impact on this overwhelming problem of climatic change.
    I just wanted to tell you I was pretty disappointed yesterday when I wanted to watch an episode of "The Ethical Man" on Youtube. As I learned in this article, your wife is part of "Friends of Colombia for Social Aid", so I reasoned you, by some indirect connection with Colombia, would agree with me regarding my disappointment with Youtube for telling me: "This video is not available in your country"!!! Why? are we in arrears with the Youtube bill? I just can't see a reason for them to ban the video around here...
    On the issue of cutting carbon emissions, I think the Brad Templeton’s kind of calculations can be taken to a byzantine level, since you can also include in the calculations every trifle you can possibly imagine: for instance, you could also include the variable “temperature of the environment” when walking/driving, so the complexity of the thermodynamic equations now step up a little, I mean, when you walk under a blistering sun, your body needs to sweat the extra heat your body is producing so the energy spent on walking have to include the component of “sweating”. Likewise, an automobile’s engine has a optimal temperature in which the energy efficiency is maximum, if you go under or over this temperature, the engine would not work with the same efficiency you’re predicting.
    You can add as many variables to the equations as you consider fit to model the reality of the phenomenon you’re studying… My point is: there is no point in trying to calculate the energy consumption by this kind of equations. The best we can do is to detect which of or daily activities are the most energy consuming and find a way to reduce them. For example, every electrical appliance in our home or office have a label with their energy consumption in VAC or Watts; we can easily identify the most consuming ones an try to use them as efficiently as possible (changing the light bulbs to fluorescent ones is just one of the changes we can do): refrigerators are often one of the most consuming (they’re on all day and their VAC is one of the highest among electrical appliances), so we could just reduce the refrigeration level to a good-enough temperature so the food won’t get spoiled but won’t be too cold either. Lets not stare the fridge while the door is open thinking: “what should I buy the next time I go to the supermarket? Oh, I remembered I’m throwing a party for my dear pal, Justin, to celebrate his achievements on the US. Will he drink as much scotch as the last time? I hope not! Should I buy Gin for his wife, should I…” the fridge will need to lower its temperature back and the bigger the difference between your kitchen’s environmental temperature and the set temp of the fridge’s thermostat, the more energy it will need to reestablish its goal temperature.
    There are not as much variables in last case’s equation; lets leave the complicated ones to the experts and hope they have a way to get their ideas/recommendations heard…

  • Comment number 24.

    Consuming calories from things above ground such as burning wood and plants and eating fruit, vegetables, and meat has a different impact on the climate than consuming calories from things below ground such as oil, natural gas and coal. If humans consumed calories from only things above ground, the carbon dioxide emitted by this caloric consumption would be consumed by plants as they use this carbon dioxide during photosynthesis and there would be no net gain of carbon dioxide in the atmosphere.

    However, burning oil, natural gas, and coal results in a net gain of carbon dioxide in the atmosphere as there aren't enough plants to consume all the the excess carbon dioxide generated from burning this stuff. One must not forget that oil, coal, and natural gas are concentrated forms of carbon and energy which is why they are used, in the first place, to power modern industry.

    My prediction is that our climate will eventually resemble the climate of the carboniferous age as we keep dumping the carbon from below ground back in the atmosphere. In my humble opinion, the only way to stop climate change is to turn back the clock to the year 1400 and live the way we did before the industrial revolution. The earth's population would probably shrink to less than 1 billion as a result.

  • Comment number 25.

    Although in your calculations you count the cost of getting (a very generous) diet to the table you don't appear to include the cost of producing petrol - and getting it from the refinery into the car, with all the infrastructure that impolies

  • Comment number 26.

    Thanks for the research Brad Templeton, but does that mean we should stop eating and walking it off? Those who eat and don't "exercise" it off, eventually crave to eat even more, get bigger pouches (tummies) to stuff even more, you guess where I am going? They eventually make the food producers to produce even more! Isn't that making matters worse?

    Dennis Junior, while I like your quote, walking and driving are not at the same level of pollution. The vehicle needs all sorts of maintenance and ultimately gets discarded with more consumption of energy (and pollution) if recycled. But the human, while eating and getting fit by walking needs basic maintenance and when eventually dies and buried, benefits the soil. Hence:

    "Walking is beneficial to humans but driving ultimately pollutes the environment the more for humans"
    - Slim316

    I really like John Comstock's comment, right on the mark, thanks.

    Anyway, back to your question, if you hadn't posted this blog, I would have suggested hypocrisy somewhere. But, hey we are all human. If we decide to get extreme with this "green" thing, then modern life may even cease, and we'll be back to 5000 B.C.

    If I were you, I would do the same. Family is more important than "green". I guess when you got home, you went for a walk with the family as well, that way, you are asserting that you're not just ethical, but fuel efficient as well.


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